Low amplitude indexing mechanism for horological instruments

ABSTRACT

A horological instrument such as an electric or electronic watch includes an indexing mechanism or dial train drive for transmitting power from an oscillating balance wheel to an index wheel. The index wheel drives the gear train of the watch and is in turn coupled to the watch hands. The indexing mechanism comprises a direct drive arrangement wherein the index wheel is driven by means of pins mounted on a plate which is fixed to the balance staff.

United States Patent 1 1 1 1 3,740,942 Wuthrich June 26, 1973 [54] LOW AMPLITUDE INDEXING MECHANISM 2,909,892 10/1959 Lucian et a1 58/28 A FOR HOROLOGICAL INSTRUMENTS 1,175,610 3/1916 Cove 58/28 A 2,962,900 12/1960 Reinhardt 58/116 R X Inventor: Paul Wulhrich, o n, Co 3,168,833 2/1965 Popovitch 58/117 x [73] Assignee: Timex Corporation, Waterbury,

ComL Primary Examiner-Richard B. W1lk1nson Assistant Examiner-Gonzales John F. [22] Flled: 1971 Attorney-Richard A. Joel [21] Appl. No.: 110,500

[57] ABSTRACT 521 US. 01. 513/28 R, 58/116 R A instrument such as electric elec- 51 1111. C1. G04c 3/04, G04b 15/00 Watch includes an indexing mechanism dial [581 Field of Search 58,28 R, 116 R, 28 B train drive for transmitting power from an oscillating 5 /2 D, 11 M; 185/3 74/15 balance wheel to an index wheel. The index wheel drives the gear train of the watch and is in turn coupled [56] References Cited to the watch hands. The indexing mechanism com- UNITED STATES PATENTS prises a direct drive arrangement wherein the index wheel is driven by means of pins mounted on a plate 3,611,707 10/1971 Scholz 58/116 R which is fixed to the balance Staff. 3,435,311 3/1969 Matsuzawa et a1. 58/28 R X 3,388,605 6/1968 3 Claims, 2 Drawing Figures Schafer 58/116 R X PATENTEU JUN 26 I973 INVENTOR. Bow. Wwumcu LOW AMPLITUDE INDEXING MECHANISM FOR HOROLOGICAL INSTRUMENTS BACKGROUND OF THE INVENTION The present invention relates to horology and more particularly to an indexing system for watches.

The balance wheel when used as a slave motor in electric or electronic watches governed by a quartz crystal oscillator, oscillates at a relatively low amplitude. It is difficult with known indexing systems to convert the relatively low amplitude oscillations of the balance wheel into rotary motion in a positive way. The indexing mechanism described hereinafter is an effi-' cient means for transmitting power from the balance wheel without the use of intermediate indexing levers. Furthermore, the problems associated with indexing systems such as maintaining the lever in draw at its extreme positions, are eliminated.

The prior art includes US. Pat. Nos. 2,900,021; 3,122,879; 3,143,848 and 3,462,942. Other pertinent patents may of course exist and the foregoing are merely cited as representative of the art in this area. It should be mentioned that applicants copending application Ser. No. 80,871 filed Oct. 15, 1970 is also of interest in this area.

SUMMARY OF THE INVENTION The present invention pertains to a low amplitude indexing mechanism for electric or electronic watches particularly quartz crystal oscillator governed watches. The balance wheel may be governed by a quartz crystal oscillator and dividing circuit of the type described in pending application Ser. No. 2,586, filed on Jan. 13, 197.0 and assigned to the same assignee as the present application. The oscillations of the balance wheel occur at relatively low amplitude and conventional indexing systems are not generally satisfactory under such conditions.

In this invention, the index wheel is directly coupled to the oscillating balance staff without the use of intermediary members. A low amplitude oscillator such as a balance wheel and a plate member are both mounted to a balance wheel staff and are oscillated thereby. The plate member includes one or more pins mounted thereon to engage the teeth of the index wheel. The index wheel teeth have a predetermined deep cut configuration to permit amplitude variations while the maximum amplitude is limited by the banking of the pins on the root of the index wheel teeth.

Accordingly, it is'an object of this invention to provide a new and improved indexing mechanism.

Another object of this invention is to provide a new and improved low amplitude indexing mechanism for quartz watches.

Other objects and advantages of the present invention will be more clearly seen when viewed in conjunction with the accompanying drawings wherein:

FIG. 1 is a top plan view of the invention with the movement of the low amplitude oscillator shown in phantom;

FIG. 2 is a partially cross-sectioned side view of the invention.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIGS. 1 and 2 of the drawings, the present invention comprises an indexing mechanism for timepieces, particularly quartz crystal watches wherein the balance wheel oscillates at a relatively low amplitude. Since such watches are intended to be extremely accurate, the indexing system must be extremely efficient and must avoid the introduction of errors; This is accomplished be means of a direct coupling between the balance wheel assembly 10 and the index wheel 11. There is no provision for the conventional index lever which would be ineffective at low balance wheel amplitudes of oscillation.

The indexing mechanism shown in the drawings includes a low amplitude oscillator 12 such as a balance wheel having either a coil or magnet (not shown) mounted thereon. The balance wheel 12 is mounted about staff 13 which is journaled at one end in bearing 14. An index pin support plate 16 is also fixedly mounted to the balance staff and spaced apart from balance wheel 12 by member 17.

The index pin support plate 16 comprises a base portion 18 and two arms 19 and 21, extendingoutwardly therefrom at an angle. A pair of pins, 22 and 23, are mounted one in each arm, 19 and 21 respectively for contacting the teeth 24 of the index wheel 11. The index pins extend at right angles from the plate 16 and alternately drive the index wheel 11 as the balance staff oscillates back and forth. The pins 22 and 23 are shown in peak position for nominal amplitude in FIG. 1, that is, one pin 22 being located about half way down the radial wall of a tooth 24. The motion of the staff 13 is transmitted through the movement of the plate 16 as shown in phantom in FIG. 1.

The index wheel teeth 24 are deep cut to permit amplitude variations which may be caused by sudden jolts and movements. The pins 22 and 23 bank against the root 26 of the teeth 24 whenever the amplitude is excessively disturbed. The pins 22 and 23 thereby limit the balance wheel amplitude to an acceptable level which is a function normally performed by an index lever.

The index wheel 11 is mounted about a staff 27 which is journaled at one end in bearing 28 in train bridge 29 while the other end is journaled in bearing 31 in the front frame 32. A drag disc 33 having a plurality of teeth 34 on the outer periphery thereof is fixedly mounted on the bottom of the index wheel 11. The teeth 34 of the disc 33 are engaged by one end of an elongated drag spring 36 to prevent reverse motion of the wheel 11' during indexing. The other end of spring 36 is mounted in support 37 which is secured to the front frame 32.

In operation, the balance staff 13 oscillates under control of an electric or electronic drive means (not shown). The pins 22 and 23 alternately engage the teeth 24 of the index wheel 11 as the index pin support plate 16 is oscillated by the balance staff 13. The pin 22 rides on the surface of a tooth 24 moving wheel 11 in the indicated direction. As the pin 22 becomes disengaged from the tooth 24, the pin 23 comes into contact with the index wheel teeth 24, see illustration in phantom. The drag spring 36 engages the disc 33 to prevent any backward movement of the index wheel 11 during operation.

If an index lever were to be used, the design would be unnecessarily complicated and the banking problems associated with such levers would be introduced. With the present invention, a jolt would cause the pin 22 or 23 to bank on the root 26 of the index tooth 24. The index wheel teeth are particularly deep cut to permit some amplitude variation due to ajolt before banksubjected to movement as the pins alternately ening occurs. gage the teeth of the index wheel, and

It is to be understood that the above-described ar- 3 mber mounted to the balance staff comprising rangements are merely illustrative examples of the apan i d i Support plate h i two arms d an plication of the principles of the invention. Numerous 5 other arrangements may be readily devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

1. An indexing mechanism for timepieces comprisindex pin projecting outwardly from each arm which engages the teeth of the index wheel to cause positive indexing thereof. 2. An indexing mechanism in accordance with claim 1 further incluing:

a drag disc mounted to one side of the index wheel and having a plurality of peripheral teeth, and

a frame having a balance staff journaled therein; a fixedly P at one end and engag' an oscillator mounted to the staff and causing movemg the disc teeth wlth other end to Prevent ment of Said Staff; rearward movement of the index wheel. an index wheel having a plurality of teeth circumferindexing mechanism in accordance with claim entially arranged thereabout, wherein said index 2 Wherelni wheel teeth are deep cut to permit pr d t i d the oscillator comprises a balance wheel having a low amplitude variation before banking of the index amplitude of oscillation. pins on the root portion thereof if the timepiece is 

1. An indexing mechanism for timepieces comprising: a frame having a balance staff journaled therein; an oscillator mounted to the staff and causing movement of said staff; an index wheel having a plurality of teeth circumferentially arranged thereabout, wherein said index wheel teeth are deep cut to permit predetermined amplitude variation before banking of the index pins on the root portion thereof if the timepiece is subjected to movement as the pins alternately engage the teeth of the index wheel, and a member mounted to the balance staff comprising an index pin support plate having two arms and an index pin projecting outwardly from each arm which engages the teeth of the index wheel to cause positive indexing thereof.
 2. An indexing mechanism in accordance with claim 1 further incluing: a drag disc mounted to one side of the index wheel and having a plurality of peripheral teeth, and a drag spring fixedly mounted at one end and engaging the disc teeth with the other end to prevent rearward movement of the index wheel.
 3. An indexing mechanism in accordance with claim 2 wherein: the oscillator comprises a balance wheel having a low amplitude of oscillation. 